The disclosure relates generally to the field of wind turbines, and more particularly to turbine blades having an aerodynamic vortex element on the flow surfaces thereof.
Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades are the primary elements of wind turbines for converting wind energy into electrical energy. The rotor blades capture kinetic energy from wind using known airfoil principles. The rotor blades in general have the cross-sectional profile of an airfoil such that, during operation, air flows over the blade producing a pressure difference between the sides. Consequently, a lift force, which is directed from a pressure side towards a suction side, acts on the blade. The lift force transmits the kinetic energy through rotational energy by generating torque on the main rotor shaft, which is geared to a generator. The generator converts the mechanical energy to electrical energy that may be deployed to a utility grid.
As wind energy systems gain more and more importance as a source of energy in recent years, areas suitable for their economical operation have become relatively scarce in a number of countries. Thus, a growing number of wind energy systems are located close to populated areas. Some known wind turbine blades may generate considerable noise during operation of the wind turbine. As a consequence, local authorities having the responsibility for granting permission for installing wind turbines may refuse to allow installation due to the noise.
Methods for reducing the noise emissions of wind energy systems have long been discussed. In some instances, the aerodynamic characteristics of the rotor blades have been changed by adding dimples, protrusions, or other structures on the surface of the blade. These structures are sometimes referred to as “vortex generators.” These devices improve the aerodynamic performance of a blade by inducing mixing of the boundary layer with the outer flow or by mixing inside the boundary layer so as to make the profile “fuller”, thereby delaying boundary layer separation, while increasing lift and reducing drag and noise at higher angles of attack. In many instances, vortex generators (VGs) are placed on the suction side of an airfoil/wind turbine rotor blade to delay the onset of this boundary layer separation. However, these types of prior art noise reducers have a variety of disadvantages, and may not adequately reduce the noise associated with typical rotor blades.
Thus, a rotor blade with improved noise-reducing features would be desired.